Structural beam



Aug. 7, 1945. D. T. DuBAssoFF STRUCTURAL BEAM Filed July 1, 1945 FIGZ INVENTOR BY 20/, P mmw ATTORNEY Patented Aug. 7, 1945 UNITED STATES PATENT OFFICE mum-i Tia mm, K223i, n. 1.

Application July. 1, 1913, Serial No. 492,999

4 Claims.

My invention relates to structural beams and has particular reference to beams employed in buildings,-bridges, etc.

My invention has for its object to provide a beam in which strong metal such as steel is used only at points of the greatest tensile strength, the beam being so constructed that its metal portions are uniformly loaded in tension, compressible stresses being taken by other materials such as wood, concrete, stone, etc., which can withstand compression but cannot resist tension to any great extent.

As is well known, in ordinary steel beams only the lowest side of the beam is subjected to the greatest tensile stress, the intermediateportions being loaded only lightly, and the upper side being under maximum compression stress. Beams designed for more or less large spans must be therefore relatively large and heavy, especially in theportions subjected to compression in order to avoid their buckling.

In my beam I provide a single strand, rod or cable, subjected to tensile stress in such a manner that the tension automatically increases as the load on the beam is increased. It is therefore possible for the beam to resist bending or deflection under load although no part of this metal rod is subjected tocompression.

Although a flexible strand such as a cable may be used with my beam, I prefer to encase the steel strand in a, rigid beam made of compressible resisting material such as wood, concrete, em. The ends of the steel core or strand are supported on pivoted arms which tend to rotate outward under load, causing further stretching of the strand and thereby resisting its bending.

My invention is more fully described in the accompanying specification and drawing in which: 1

Fig. 1 is a sectional elevational view of my beam; x;

Fig. 2 is a transverse sectional" ew of the same;

Fig. 3 is an elevational view of a modified beam;

Fig. 4 is a fractional sectional view oi another modification; r

Fig. 5 is a sectional elevational view of still another modification;

Fig. 6 is a fractional view. of a modified beam;

Fig. '7 is an elevational view oi another modification- My beam as shown in Figs. 1 and 2 consists of a metal strand or rod I with an initial deflection calculated toreduce the tensile stress at .the middle point of the rod. The rod is encased in a rigid beam 2 which may be made of wood, concrete or similar material lighter and less expensive than steel. The object of the enclosure 2 is to render the beam rigid to distribute the load more uniformly on the metal strand, and to provide a straight surface at the top for laying floor, etc., also to facilitate handling of the composite beam during erection of the building.

The ends of the rod l are pivotally connected at 3 to short metal arms I, the other ends of the arms being pivoted at 5 to a base plate 6 on top of a foundation or wall I. The arms 4 are inclined outward as shown so that they tend to rotate outward when load is applied to the beam 2, thereby stretching the rod (1 and increasing its tensile stress and preventing its bending or de flection.

Due to the fact that the rod l is subjected to the maximum tensile stress under a given load, considerable reduction in weight of steel is obtained as compared with an ordinary beam with its varying stresses.

A modified construction is shown in Fig. 3, cables t being used instead of the rod l, the cables being tightly stretched between the inclined supporting arms l to which the ends of the cables are attached. A common beam 9 is placed on top anchored to the ends of the cables for providing rigid support for the floors above. The beam 9 passes over the ends of the cables on top of the walls l.

In another modification shown in Fig. 4 the rod I0 is held by nuts II or by other fastening means in end plates l2, resting against the ends of the wooden beam 2. The rod I0 is not subjected to stretching under load but is prevented from sagging under load. p

A straight rod I3 is shown in Fig. 5, reinforced by a stifiening compression beam H anchored at the ends to the ends of the rod l3. Path of rotation of the arms 4 is shown in dotted lines it.

With my construction of beams considerable saving in steel is efiected since the steel rod. or strand is subjected only to the tensile stress and not to the bending or breaking as in ordinary beams.

Another construction is shown in Fig. 6, the

beam l6 having an overhanging extension I! resting on the pivoted end 3 of the strand I. The

link I is provided at the lower end with a. rounded load tends to rotate the links 4 downward, thereby stretching the strand I.

asso ess her made of a non-metallic material adapted to pended claims.

I claim as my invention:

1. A structural beam comprising an elongated metal member: an enclosure for the metal member made of a non-metallic material adapted to resist longitudinal compression and forming a composite beam with the elongated member, the

ends 0! the metal member protruding outwardly from the enclosure; links pivotally connected to the ends of the elongated member extending inwardly'at an angle to the elongated member; supports for the lower ends of the links; theenclosure having vertical .shoulders at the ends abutting the lower ends of the links and having further horizontal extensions resting on the pivoted ends of the elongated member.

2. A structural beam comprising an elongated metal member; an enclosure for the metal member made 01' a non-metallic material adapted to resist longitudinal compression and forming a composite beam with the elongated member; the ends oi the metalmember protruding outwardly -i'rom the enclosure; links pivotally connected to the ends of the elongated member extending inwardb at an angle to the elongated member; supports lor the lower ends of thelinks; the enclosure ha shoulders engaging the lower ends oi-the links for resisting horizontal movement of the links; and means to move the upper ends of the links downward by the downward movement oi the beam.

3. A structural beam comprising an elongated metal member; an enclosure for the metal memreslst a longitudinal compression and forming a composite beam'with the elongated members;

the ends or the metal memberfprotruding outwards from the enclosure; links pivotally connected to the ends of the elongated member extending inwardly at anangle'to theielongated member; supports for the lower ends of the links; andmeansattheendsorthebeamtodepress the pivoted ends of the. elongated member whe the beam is under load.

4. A structural beam comprising an elongated metal member; an enclosure for the metal member made of a non-metallic material adapted to resist longitudinal compression and forming a composite beam with the elongated member; the

end of the metal member protruding outwardly from the enclosure; links pivotally connected to ,nm'mr 'r. nunessorr. 

